and you thought this was going to be easy…Cygnus X is mind-boggling in a bunch of ways. First, as always, is the astounding image returned by a space telescope, in this case the Spitzer Space Telescope, an infrared earth-orbiting observatory. Then there is the issue of what we are actually looking at: Cygnux X, as it turns out, is a star-factory or star-nursery, that is, a region of space that produces new stars out of clouds of interstellar gas and dust. Impressive, to be sure, but here is something even more impressive: Cygnus X contains NML Cygni, the largest star known. NML Cygni is 1,650 times as large as our sun; its radius is 7.67 astronomical units across. That’s right; if NML-C was our star, we would lie well within its surface. Cygnus X contains other massive protostars and lies 4,600 light years from earth. RT

The CEN (NGC 6543) is a planetary nebula, which means it is a ring of gases that is being ionized by a nearby star, in this case the remnants of a red giant (or possibly a binary star system) that died in an extremely complex process. What is certain is that the CEN has the most intricate halo of gases ever observed in a planetary nebula.

Here is RT’s effort at reconstructing the star’s death: the original star expanded into a red giant, sending out long trails of its outer material into space, where they encountered interstellar gas and dust that broke the trails up into spectacular streamers and knots of gas. Then the star began a series of explosions, ejecting more material to form a set of shells surrounding the star. These events took place 1,500-1,000 years ago; the CEN is located 3,000 light-years from earth.

It’s been decades since Alexei Leonov became the first person to walk in space (on March 18, 1965), but somehow the thrill of seeing someone floating (or working) in space has never vanished. The gentleman in this picture is commander Sergey Alexandrovich Volkov (photographed by Flight Engineer Dmitriyevich Oleg Kononenko) during expedition 17 to the ISS. Kononenko is at the end of the manual Strela crane operated by the commander; the crane has a mass of around 45kg. An orange safety lifeline along the boom fastens the men to the Space Station.

It’s remarkable what we can accomplish when we set our minds to it. RT

(And, for the record, the first woman to walk in space was Soviet cosmonaut Svetlana Savitskaya–on July 17, 1984.)

The attention being paid to the rover Curiosity’s arrival on Mars is understandable, but what’s going on elsewhere in the cosmos? Here’s the latest word on the Kepler spacecraft (which is looking for earth-sized planets outside our solar system): Kepler has discovered 74 confirmed planets, of which two are earth-sized (though neither is in its star’s habitable zone). The total number of exoplanets discovered to date: 777.

Now here is where the numbers really get interesting. Analysis of exoplanet data has led to the following conclusions: the Milky Way contains 100 billion or so stars; each of these stars is estimated to have 1.6 planets. Crunching the numbers, this means that our galaxy is estimated to contain 160 billion solar-bound planets.

Let’s take this a bit further. Many conditions are necessary for the formation of life on a planet. One of the most important is that a planet orbit a star of the correct type, spectral class “G” to “mid-K.” Five to ten percent of stars fall into this range; applying this filter leaves us with 8-16 billion candidate planets.

And here’s another consideration: the planet must fall within a star’s habitable zone. The Kepler team estimates that at least half a billion planets meet this criterion.

There are other requirements candidates have to meet: their star must have a high metallicity, low variation, and a stable habitable zone. The planet must also have a high mass, an orbital inclination not too far off the ecliptic, and geochemistry capable of producing amino acids, the building blocks of life. Did I mention surface water (lots of it)?

OK, it’s a lot. But how many New Earths do we really need? A hundred? A thousand? Heck, the discovery of just one would send shivers down our backs, especially if the particular planet features copious oxygen in its atmosphere. And I won’t even speculate what the response would be if we found chlorophyll in its chemical signature.

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And after all, there is the question of how to get there. That’s why the photograph above was taken by the Huygens probe, which landed on Saturn’s moon Titan. We can get there.

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Photo: Composite Image Taken During Huygen’s Descent to the Surface. WikiCmns; NASA/JPL Public Domain with attribution.